It depends on who you are facing. Dialga has a weakness to only ice/fighting, and Palkia has a weakness to only dragon/fighting. Dialga's steel part counters the dragon, and Palkia's water counters the Ice.
Stat-wise, Dialga is more offensive and Palkia is Defensive. Otherwise, they learn [pretty much] the same types of moves with the same power.
Personally, I would say that Dialga is better, but technically, they are equal.
Sorry, Where I put Palkia is weak to water/fighting, I meant to put weak to Dragon/Fighting. I edited it though, so its all good.
[Edited by Ho-Oh2224, 4/30/2007 4:13:48 PM]
im agreeing on this 1
but in my point of veiw... in a battle:
Dilaga=
Palkia=
but thats just me